Method of operating blast furnaces



Sept. 1, 1925.

S. B. SHELDON METHOD OF OPERATING BLAST FURNACES Filed Oct. 11. 1925 2 Sheets-Sheet 1 Sept. l,- 1925;

' 1,552,179 5. B. sun-100m I METHOD OF OPERATING BLAST FURNACES 2 Sheds-Sheet 2 Filed Oct. 1923 v m, I Q R f 1 1, a I

'tuyeres simultaneously.

Patented Sept. '1, 1925 smear. nnnrunr snnLnoN, or DULUTH, MINNESOTA.

nnrnon or OPERATING BLAs'r FURNACES.

Application filed October 11, 1923. Serial No. 888,000.

To all whom, it may concern:

Be it known that I, SAMUEL B. SHELDoN, a citizen'of the United States, residin at Duluth, in the county of-St.'Lou'is and btate of Minnesota, have invented certain new and useful Improvements in Methods of Operating Blast F urnaces, of which the following is a-specification- V This. invention relatesto. a new and improved method of operating blast furnaces and more specifically to a method of applying the air blast to such furnaces.

The blast furnace now in general'use is provided with a plurality of tuye'res, usually 10 or 12, which are connected by bootlegs to a bustle pipe. According to common practice, the air is introduced through all of the From consideration' of Bernouilis law of thefiow of gases, it is manifest that the tuyeres more remote from the point where the main air line-joins the bustle pipe can never pass air intothe furnace with the same velocity as tuyeres nearer the point of ingress of the air.

, Further, it is found in actual practice that although the same amount and pressure of air may be supplied to tuyeres continuously, the resultant pressure in the tuyere will differ from time to time. This is believed to be due to what is called in ractice blast wandering in the furnace. large portion of the blast follows a certain upward path through the furnace because at that particular time it is the path of least resistance. This will continue until some other path of lesser resistance is established. .It is well known amon furnace operators thatvduring only relativelyshort Periods of time is the entire cross-section o the hearth performing for uniform melting. This blast wandering and lack of uniformity induces slips,

' bangs and all'the various detrimental phenomena encountered in blast furnace operation. I r

If it were possible .to cause the point or points of ingress of th'e air into the furnace to be held stationary while the furnace itself revolved, then every point inthe circumference of the hearth would be subjected to the same conditions, in so far as air blastingand consequent combustion is concerned. Due to structural difiiculties inherent in present blast furnaces, such a course is obvious ly impractical. Substantially the same result can be obtained, however, by maintainchange continuouslythroughout the process,

fully opened and additional tuyeres being others partially closed off so that the zone of full pressure air introduction travels progressively around the furnace.

It is an object of the present invent-ion to provide a method of blastfurnaee operation whereby blast air will be supplied'substantially uniformly to the different portions of the circumference 'of the furnace.

It is. an additional object to provide a .method of this character in which air under fullpressure is supplied to a portion onlyof the circumference of the furnace at a time, the port-ion continuously changing throughout" the process.

It is an additional object to provide amethod of this character in which the zone of air blast, in effect, revolves about the furnace during operation, I

Other and further objects will appear as the description proceeds.

I have illustrated in the accompanying drawings portions of a blast furnace adapted to with.-

In the drawings permit the use of my invention there- Figure 1 is a vertical section through the lower-portion of a blast furnace; and

Figure 2 is a somewhat diagrammatic plan view taken approximately on the line of t-uyercs of Figure 1.

Referring now nace 3 is provided with the bustle pipe 4 from which the bootlegs 5 lead to the tuyeres-fi. The air main 7 leads into the bustle pipe 6 as shown in Figure 2. The bootlegs 5 are each provided with the valve 8 adapted to selectively close off the bootle As shown in Figure 2,- the furnace se ected for the purpose of illustration is provided with twe ve tu'yeres 6 which for the purlpose of discussion have been lettered A Itwill be clear that when the air is introto the drawings, the furduced into the bustle pipe or main 7, if all the valves in the bootlegs are open, a greater quantity of air will pass through tu'eres F and G than through tuyeres A and which latter are most distant from the point of introduction of the air. Consequently there will be a permanent variation of the blast in the furnace. If the valves controlling tuyeres G to L are shut off, all air will enterthrough tuyeres A to F and the amount entering through each tuyere "will be increased. If the valves controlling tuyeres G and L are not entirely shut olf but are nearly closed so as to admit merely enough air to prevent slag forming in their nozzles, the effect upon the introduction of air through tuyeres A to F is substantially the same as if tuyeres G and L were entirely cut out.

If after a predetermined period of time, the valve controlling tuyere F is nearly closed and that controlling tuyere A is fully opened, and after a further similar lapse of time the valve controlling tuyere E is nearly closed and that controlling tuyere K fully opened, and this process is continued the air blast will, in effect, revolve around the periphery :of the hearth. The blast will cover the entire circumference, not simultaneously but at regular intervals. All parts of the furnace will be subjected to. the same regular irregularity and the effect will. be substantially the same as if the points of introduction of the air remained stationary while the furnace revolved.

By controlling the air blast in this manner the production of channels causing blast wandering in the furnace will be minimized since the point of introduction of the air will be consequently changing. This will resuit in amore uniform operation and will reduce slips, hangs and other detrimental phenomena encountered'in blast furnace operatlon.

I claim:

1. The method of blast furnace operation comprising the application of blast air under full working pressure through a portion only of the periphery, the portion changing throughout the process.

2. The method of blast furnace operation comprising the application of blast air under full working pressure through a portion only of the periphery, the portion changing throughout the process, and admitting air under lesser pressure through the remainder of the periphery. I

3. The method of blast furnace operation comprising the application of blast air under full working pressure through a portion only of the periphery, the portion changing its location throughout the process, but remaining substantially constant in amount.

4. The method of blast furnace operation comprising the application of blast air un-. der full working pressure through a portion only of the periphery, the po'rtionprogressing around the furnace during the process.

5. The method of blast furnace operation comprising the application of blast air under full Working pressure through a portion only of the perlphery, the portion progress- Signed at Duluth, Minnesota, this 1st day of October, 1923. v

SAMUEL BER-TEAM SHELDON. 

